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United States Patent |
5,049,368
|
Turner, Jr.
|
September 17, 1991
|
Method of applying primers onto the body flange and windshield of
vehicles
Abstract
A method of applying a clear glass primer material and then a black glass
primer material onto the marginal edge of a windshield and/or rear window
of a vehicle, and for applying a black metal primer onto the mating body
flanges of the vehicle, in which an airless, cross cut-type flat pattern
nozzle is employed to discharge such primer materials at pressures
substantially below the normal pressures at which airless spray nozzles
are operated to produce an atomized stream. A triangular-shaped liquid
film emission of the primer materials is produced by such an airless spray
nozzle, operated at low pressures, which forms a well defined pattern on
both the windshield and the associated body flanges without splashing or
overspray onto the surrounding surfaces.
Inventors:
|
Turner, Jr.; Herman E. (Wellington, OH)
|
Assignee:
|
Nordson Corporation (Westlake, OH)
|
Appl. No.:
|
492782 |
Filed:
|
March 12, 1990 |
Current U.S. Class: |
427/424; 427/427.2; 427/427.3 |
Intern'l Class: |
B05D 001/02 |
Field of Search: |
427/421,424,420
|
References Cited
U.S. Patent Documents
3852095 | Dec., 1974 | Hogstrom | 117/43.
|
4337281 | Jun., 1982 | Boone | 427/236.
|
4753819 | Jun., 1988 | Shimada | 427/96.
|
4857367 | Aug., 1989 | Thorn et al. | 426/348.
|
4880663 | Nov., 1989 | Shimada | 427/96.
|
Other References
English Translation of Japanese Patent Publication 2-10595, 1990.
|
Primary Examiner: Beck; Shrive
Assistant Examiner: Bashore; Alain
Attorney, Agent or Firm: Wood, Herron & Evans
Claims
What is claimed is:
1. The method of applying liquid primer material onto the body flange of a
vehicle in preparation for attachment to a section of glass, comprising:
supplying the liquid primer material to an airless nozzle means;
controlling the supply pressure of the liquid primer material to the nozzle
means such that a liquid film emission is discharged from the nozzle means
which is substantially free of atomized particles of liquid primer
material;
positioning the body flange of the vehicle in the path of the liquid film
emission discharged from the nozzle means;
producing relative movement between the nozzle means and the body flange of
the vehicle to obtain a uniform, splash-free coating of the liquid primer
material on a predetermined area of the body flange while substantially
avoiding the application of the liquid primer material outside of the
predetermined area of the body flange.
2. The method of claim 1 in which said step of supplying the liquid primer
material comprises supplying a liquid primer material having a viscosity
in the range of about 20 to 40 cps.
3. The method of claim 2 in which said step of controlling the supply
pressure comprises supplying the liquid primer material at a pressure in
the range of the equivalent of about 1.41 to 2.11 Kg/cm.sup.2.
4. The method of claim 2 in which said step of positioning the body flange
comprises positioning the body flange at a distance from said nozzle means
in the range of the equivalent of about 10 mm to 20 mm.
Description
FIELD OF THE INVENTION
This invention relates to the method of preparing the windshield and
associated body flange of automobiles or other vehicles for bonding to one
another, and, more particularly, to a method of applying glass primer
coatings onto the marginal edge of the windshield or other glass elements
of the vehicle, and a metal primer coating onto the associated body
flanges of the vehicle, in preparation of adhesively bonding the glass and
body flange together.
BACKGROUND OF THE INVENTION
The assembly of the windshield, rear window and other glass elements of a
vehicle to their associated body flanges is an important operation in the
manufacture of vehicles, particularly from a safety standpoint. The
federal government requires vehicles to pass a windshield retention test,
and the materials which are used to assemble the windshield to the body
flanges of the vehicle must be properly applied to pass the test and avoid
expensive recalls.
The preparation of the windshield and associated body flange of a vehicle
for assembly involves a number of operations. With respect to the
windshield, glass manufacturers supply automotive windshields with a
"blackened area", i.e., an area of predetermined width along the marginal
edge of the windshield which is covered with a black, ceramic frit having
a roughened surface. It is the responsibility of the automotive
manufacturer to prepare this blackened area for assembly to the body
flange of the vehicle. First, a clear glass primer material is applied to
the blackened area, usually with a wet brush manipulated by a robot or
other automated brush mover. Preferably, a felt wick is dragged by the
robot immediately behind the wet brush to wipe dry the clear glass primer,
and to force the clear glass primer into the roughened surface of the
blackened area. The clear glass primer prepares the blackened area for
receipt of a coat of black glass primer material as described below.
One problem which has been experienced with the application of clear glass
primer onto the blackened area of the windshield is that the primer is not
readily visible, and it is difficult to determine how much clear glass
primer has been applied and whether the desired amount of the surface area
of the ceramic frit has been covered. An inadequate amount or film build
of clear glass primer, and/or an incomplete covering of the surface area
having the ceramic frit, can result in a failure of the windshield
retention test after the windshield is installed.
The next step in the preparation of the windshield for assembly to the
vehicle body flange involves the application of a black glass primer over
the area which had been previously coated with the clear glass primer. One
method of applying the black glass primer to the windshield involves a
manual operation using a flow brush or the like. This method is
labor-intensive, and human applicators are prone to dripping some of the
black glass primer from the brush onto areas outside of the blackened,
ceramic frit. Such drips onto the clear portion of the glass are
unacceptable and may require rejection of the windshield for use.
Another means of applying the black glass primer onto the marginal edge of
the windshield is disclosed, for example, in U.S. Pat. No. 4,857,367 to
Thorn et al. This patent discloses an apparatus which comprises a liquid
spray nozzle, an air nozzle and a vacuum device which are movable as a
unit upon a robot arm relative to the marginal edge of a windshield. The
liquid nozzle sprays atomized black glass primer material in a triangular
pattern onto the edge of the windshield. In order to prevent oversprayed,
atomized black glass primer from being deposited onto the clear portion of
the windshield, the air nozzle directs a stream of air from the interior
of the windshield outwardly so as to force any oversprayed primer
particles away from the interior or clear portion of the windshield. The
vacuum device is located beneath and alongside the peripheral edge of the
windshield to draw a vacuum thereat and collect the oversprayed primer
particles which do not adhere to the glass.
While systems of the type disclosed in U.S. Pat. No. 4,857,367 are intended
to avoid the drip-page problem obtained with manual application of the
black primer, it has been found that the application of at least some
black glass primer onto the clear portion of the windshield can still
occur. The vacuum device is not completely effective in collecting the
oversprayed, atomized black glass primer discharged from the liquid
nozzle, and some of this oversprayed black glass primer can fall onto the
clear portion of the windshield.
Another aspect of the windshield assembly operation is the preparation of
the body flange of the vehicle which mounts the windshield. A black metal
primer is applied to this body flange, typically using a flow brush and/or
an atomized spray type of coating dispenser such as a spray gun, both of
which are manipulated manually by an operator. The application of the
black metal primer must be performed with great care because the exterior
surfaces of the vehicle have received a finish coat of paint before the
windshield is installed. Drippage or running of the black primer from the
flow brush onto the "Class A" or painted surface of the vehicle presents a
major quality control problem. In addition to the drippage problem, manual
application of the black metal primer with a brush can also result in too
much material being applied to the body flange, the formation of streaks
thereon and/or a film build-up along one or more areas of the flange.
While dispensers such as spray guns which produce an atomized spray of the
black metal primer can be utilized along some areas of the body flange of
the vehicle, the problem of oversprayed primer from such guns prohibits
their use anywhere near the finished, painted surface of the vehicle.
SUMMARY OF THE INVENTION
It is therefore among the objectives of this invention to provide a method
of applying the primer coatings to the marginal edge of the windshield or
other glass sections of a vehicle, and to their associated body flanges,
in which a consistent, uniform coating of primer material is produced and
in which dripping, running and/or overspray of the primer material is
avoided.
These objectives are accomplished in the method of applying a clear glass
primer and then a black glass primer onto the marginal edge of a
windshield, rear window or other glass sections of a vehicle, and for
applying a black metal primer onto the mating body flanges of the vehicle,
in which an airless, flat spray nozzle is employed to discharge these
liquid primer materials at supply pressures substantially below the
pressures at which such airless flat spray nozzles are normally operated.
A triangular-shaped liquid film emission is produced by such flat spray
airless nozzle, operated at relatively low pressures, which forms a well
defined, flat pattern of primer materials on both the windshield and the
associated body flange without splashing or overspray onto the surrounding
surfaces.
The method of this invention is generally related to the method of coating
printed circuitboards disclosed in U.S. Pat. Nos. 4,753,819 and 4,880,663,
both to Shimada, which are owned by the same assignee as this invention,
and the disclosures of which are incorporated by reference in their
entireties herein. As discussed in detail in the Shimada patents, coating
materials such as paint or primers are often "sprayed" onto printed
circuitboards and other substrates. Spraying methods are generally
classified into two types, i.e., air spraying and airless spraying. In air
spraying, a stream of coating material is impacted by separate streams of
air to atomize the material for deposition onto a substrate. The airless
spraying method involves first pressurizing the coating material, and then
atomizing the material into the atmosphere by the ejection force of the
pressurized liquid at the discharge orifice of a nozzle.
The spraying of paint and other coatings, using either the air spraying or
airless spraying technique, utilizes the atomized part of the coating for
application onto the substrate. This atomized part is an area where an
essentially infinite number of fine particles of the coating material are
suspended in the atmosphere. Because these fine particles are floating
almost uniformly, i.e., at equal density, a relatively uniform coating of
the paint material can be applied onto a substrate. The primary problem
with applying coating material in atomized form, as discussed above with
reference to U.S. Pat. No. 4,857,367 to Thorn et al, is that there is no
distinct boundary to the mist of fine coating particles and thus the
surface to be coated must either be masked, or an air blower or similar
device must be provided to direct air against the oversprayed particles,
in order to avoid the application of such oversprayed paint particles onto
areas where they are not desired.
As set forth in the U.S. Pat. Nos. 4,753,819 and 4,880,663 Shimada patents,
it was discovered that a uniform thickness pattern of materials with a
certain viscosity could be produced having good edge definition, i.e.,
sharply defined boundaries, without overspray or splashing of the coating
material, by employing flat pattern, airless spray nozzles operated at
pressures well below the pressures at which they are normally operated to
obtain atomized coating particles. For example, whereas flat pattern,
airless-type nozzles are conventionally operated at pressures on the order
of about 35 Kg/cm.sup.2 (500 psi) or higher, it was discovered that a
uniform, splash-free liquid coating emission could be obtained with such
airless nozzles operated at pressures in the range of about 2 Kg/cm.sup.2
to 8 Kg/cm.sup.2, or about 28 psi to 114 psi, for coating materials having
a viscosity in the range of about 100-155 cps.
In the method of this invention, primer materials having a much lower
viscosity than the materials disclosed in the Shimada patents are employed
in connection with the preparation of the marginal edge of a windshield or
other glass section of a vehicle, and the associated body flanges, for
assembly. The clear glass primer material applied during the first step of
preparing a windshield for assembly has a viscosity in the range of about
5-15 cps, and the black glass primer applied atop the clear glass primer
has a viscosity in the range of about 10-20 cps. The black metal primer
applied to the body flange of the vehicle has a viscosity in the range of
about 20-40 cps. In the presently preferred embodiment, the clear glass
primer is supplied to a flat pattern, airless spray nozzle at a pressure
in the range of about 0.56-0.84 Kg/cm.sup.2 (8-12 psi) with a nozzle being
positioned about 5-8 mm (0.196-0.315 in.) from the surface of the glass.
The black glass primer applied to the windshield, and the black metal
primer applied to the body flange, are each supplied to the same type of
airless spray nozzle at a pressure in the range of about 1.41-2.11
Kg/cm.sup.2 (20-30 psi) with the nozzle being positioned in the range of
about 10-20 mm (0.393-0.787 in.) from the glass or body flange.
It has been found that both the clear glass primer and black glass primer
applied to the windshield, and the black metal primer applied to the body
flange, can be discharged from a flat spray, airless nozzle under the
conditions mentioned above in a liquid film emission which produces a
uniform coating having good edge definition on the glass and body flanges
with essentially no splashing or overspray of material onto the clear
surface of the windshield or the finished, painted areas of the vehicle.
DESCRIPTION OF THE DRAWINGS
The structure, operation and advantages of the presently preferred
embodiment of this invention will become further apparent upon
consideration of the following description, taken in conjunction with the
accompanying drawings, wherein:
FIG. 1 is a schematic view of the application of one of the glass primer
materials onto the marginal edge of a windshield of a vehicle;
FIG. 2 is a schematic view of the application of a primer material onto the
body flange of the vehicle which mounts the windshield depicted in FIG. 1;
FIG. 3 is a front view of a triangular-shaped, liquid film emission of
primer material dispensed in accordance with the method of this invention;
FIG. 4 is a side view of the triangular-shaped liquid film emission of FIG.
3;
FIG. 5A is a schematic view of the application of a clear glass primer onto
a windshield;
FIG. 5B is a schematic view of the application of a black glass primer onto
the windshield of FIG. 5A; and
FIG. 5C is a schematic view of the application of a black metal primer onto
the body flange of a vehicle.
DETAILED DESCRIPTION OF THE INVENTION
Referring now to the Figs., a portion of an industrial robot arm 10 of the
type currently employed in the assembly of automobiles or other vehicles
is schematically illustrated. The details of construction of the robot arm
10 form no part of this invention per se, and therefore the detailed
structure of the robot arm 10 is not described herein. The robot arm 10
manipulates a spray gun 14 having an airless spray nozzle 16. Preferably,
the airless spray nozzle 16 is a cross cut nozzle having a discharge
outlet 18 which produces a flat spray pattern. Airless, flat spray nozzles
16 of this type are well known and widely used commercially, and the
details of the construction of such nozzles form no part of this invention
per se. One type of airless, flat spray nozzle 16 which is suitable for
use in this invention is disclosed in U S. Pat. No. 4,337,281 to Boone,
owned by the assignee of this invention, the disclosure of which is
incorporated by reference in its entirety herein.
Airless spray nozzles of the type disclosed in U.S. Pat. No. 4,337,281 are
normally operated at relatively high pressures, i.e., on the order of
about 35 Kg/cm.sup.2 (500 psi) or higher depending upon the viscosity of
the material, in order to obtain atomization of the liquid coating
material discharged therefrom. This invention is predicated upon the
concept of operating the airless spray nozzle 16 at significantly lower
pressures so as to obtain a liquid film emission 20 of the type
illustrated in FIGS. 3 and 4. This liquid film emission 20 is a
triangular-shaped liquid film, which is substantially free of atomized
particles throughout a distance L extending from the discharge outlet 18
of the airless spray nozzle 16 to a location generally designated as 22
having a width W. Below this location or line 22, the liquid film emission
20 begins to break up into atomized particles of primer material. As
described below, the discharge outlet 18 of nozzle 16 is positioned above
the surface to be coated at a distance no greater than L so that a uniform
liquid film emission, without atomized particles, is applied to such
surface.
The method of this invention involves the production of a triangular-shaped
liquid film emission for each of three different primer materials, which
are substantially the same as the liquid film emission 20 illustrated in
FIGS. 3 and 4. A triangular-shaped liquid film emission 20a of a clear
glass primer material and a triangular-shaped liquid film emission 20b of
a black glass primer material are produced for application onto the
marginal edge 24 of a glass windshield 26 as viewed in FIGS. 5A and 5B,
respectively. A triangular-shaped liquid film emission 20c of a black
metal primer is also produced by the method of this invention for
application onto the body flange 28 of a vehicle 30 which mounts the
windshield 26.
One example in which liquid film emissions 20a, b and c were obtained with
the method of this invention is given below.
______________________________________
Example I
______________________________________
A. Clear Glass Primer For Windshield:
Material: "Betaseal" glass primer 435.18
Essex Specialty Products, Inc.
Troy, Michigan
Viscosity: 9 cps
Pressure: .56-.84 Kg/cm.sup.2 (8-12 psi)
Stand-off: 5 mm (.196 in.)
Pattern Width:
15 mm (.591 in.)
B. Black Glass Primer For Windshield:
Material: "Betaseal" glass primer 435.20
Essex Specialty Products, Inc.
Troy, Michigan
Viscosity: 15 cps
Pressure: 1.41-2.11 Kg/cm.sup.2 (20-30 psi)
Stand-off: 13 mm (.512 in.)
Pattern Width:
15 mm (.591 in.)
C. Black Metal Primer For Body Flange:
Material: "Betaseal" Painted Metal
Primer 435.34
Essex Specialty Products, Inc.
Troy, Michigan
Viscosity: 30 cps
Pressure: 1.41-2.11 Kg/cm.sup.2 (20-30 psi)
Stand-off: 17 mm (.669 in.)
Pattern Width:
19 mm (.748 in.)
______________________________________
With reference to Example I and FIGS. 1, 2, and 5A-5C, the method of
applying the various primer materials to the windshield 26 and to the body
flange 28 proceeds as follows. The "clear glass primer" referenced in
Example I is applied first to the marginal edge 24 of windshield 26. See
FIGS. 1 and 5A. The robot arm 10 positions the spray gun 14 so that the
airless spray nozzle 16 is located at a distance or stand-off in the range
of about 5-8 mm, and preferably about 5 mm, above the marginal edge 24 of
windshield 26. This stand-off is preferably no greater than the distance L
of the liquid film emission 20a, i.e., the distance between the discharge
orifice 18 of spray nozzle 16 and the line 22 of the liquid film emission
20, so that essentially no atomized particles of the clear glass primer
are applied to the windshield 26. At a stand-off of about 5-8 mm, the
pattern width of the clear glass primer on the marginal edge 24 of the
windshield 26 is in the range of about 15- 16 mm (0.591-0.630 in.).
For purposes of the present discussion, it is assumed that the discharge
orifice 18 of spray nozzle 16 is positioned at about a distance "L" from
the windshield 26 in FIGS. 5A and 5B, and from the body flange 28 in FIG.
5C, as that distance L is defined with reference to FIGS. 3 and 4. At this
stand-off or distance from the windshield 26 or body flange 28, the spray
nozzle 16 produces liquid film emissions 20a, b or c of primer materials
which have a maximum width W at the surface of the windshield 26 or body
flange 28 before the emissions 20a, b or c begin to break up into atomized
particles. See FIG. 3. It should be understood that the width of the
primer material on the windshield 26 and/or body flange 28 could be varied
by decreasing the stand-off of spray nozzle 16 within this distance L, if
a narrower coating of primer material on such surfaces is desired.
The pressure at which the clear glass primer is supplied to the airless
spray nozzle 16 is preferably in the range of about 0.56-0.84 Kg/cm.sup.2
(8-12 psi), with the viscosity of such material being in the range of
about 5-15 cps, and preferably about 9 cps. The flow rate of clear glass
primer supplied to the spray nozzle 16 varies with the speed at which the
spray gun 14 is advanced along the marginal edge 24 of windshield 26 by
the robot arm 10. If the spray gun 14 is moved at a rate of about 20
lineal inches per second by the robot arm 10 relative to the windshield
26, the flow rate of clear glass primer material to the spray nozzle 16 is
on the order of about 0.005 gallons per minute. The flow rate of clear
glass primer material to the spray nozzle 16 is increased as the lineal
speed at which the spray gun 14 is advanced along the windshield 26
increases. For example, if the spray gun 14 and spray nozzle 16 are
advanced along the marginal edge 24 of windshield 26 by the robot arm 10
at a rate of about 40 lineal inches per second, the flow rate of clear
glass primer material to the spray nozzle 16 is on the order of about
0.011 gallons per minute.
After the clear glass primer material is applied to the edge 24 of
windshield 26, and "wiped dry" by suitable means such as a felt wiper (not
shown) carried by the robot arm 10, the windshield 26 is then ready for
the application of a black glass primer. In accordance with the method of
this invention, the black glass primer having a viscosity in the range of
about 10-20 cps, and preferably about 15 cps, is applied by an airless
spray nozzle 16 positioned about 15-20 mm (0.591-0.787 in.), and
preferably about 13 mm (0.512 in.), from the surface of the marginal edge
24 of windshield 26. This distance or stand-off is no greater than the
distance L from the discharge orifice 18 of the spray nozzle 16, and such
distance L is greater than the distance L for the clear glass primer
because the black glass primer has a higher viscosity. At a stand-off of
about 15-20 mm, a pattern width is produced on the marginal edge 24 of
windshield 26 in the range of about 15- 16 mm, (0.591-0.630 in.), and
preferably about 15 mm. The black glass primer is delivered to the spray
nozzle 16 at a pressure in the range of about 1.41-2.11 Kg/cm.sup.2 (20-30
psi) in order to obtain the liquid film emission 20b illustrated in FIG.
5B. In the presently preferred embodiment, the flow rates at which the
black glass primer is delivered to the spray nozzle 16 are dependent upon
the speed of lineal movement of the spray gun 14 and spray nozzle 16 along
the peripheral edge of the windshield 26. Preferably, the black glass
primer is applied at a flow rate of about 0.02 gpm at a speed of about 20
lineal inches per second up to about 0.045 gpm at a speed of about 40
lineal inches per second.
As illustrated in FIGS. 2 and 5C, the application of the black metal primer
to the body flange 28 of the automobile 30 is also accomplished with a
spray gun 14 and a spray nozzle 16 manipulated by the robot arm 10 to
produce a liquid film emission 20c. The viscosity of the black glass
primer is in the range of about 20-40 cps, and preferably about 30 cps.
The black glass primer is supplied to the spray gun 14 at a pressure in
the range of about 1.41-2.11 Kg/cm.sup.2 (20-30 psi), and is discharged
from the nozzle 14 at a stand-off or distance in the range of about 10-20
mm (0.394-0.787 in.), and preferably about 17 mm (0.669 in.), above the
body flange 28.
The flow rate of black metal primer supplied to the spray nozzle 16 is also
dependent upon the speed of linear movement of the spray gun 14 and spray
nozzle 16 with respect to the body flange 28. Preferably, the black body
flange primer is supplied to the spray nozzle 16 at flow rates of between
about 0.020 and 0.045 gpm with the spray gun 14 and spray nozzle 16
advanced along the body flange 28 at speeds in the range of about 20 to 40
lineal inches per second.
In accordance with the teachings of the method of this invention, it has
been discovered that splash-free, uniform thickness coatings of primer
material can be applied to the windshield and associated body flanges of
automobiles and other vehicles provided that the pressure at which the
primer materials are supplied to the airless spray nozzles 16 herein are
in the range of about 0.56-2.11 Kg/cm.sup.2 (8-30 psi) for materials
having a viscosity in the range of about 5-40 cps, and wherein the
stand-off or distance of the discharge orifice 18 of the spray nozzle 16
from the surface of the windshield 26 or body flange 28 is in the range of
about 5-20 mm (0.196-1.787 in.). Under these conditions, well defined
liquid film emissions 20a, b and c are formed, which are substantially
free of atomized particles, and which produce a splash-free coating upon
the windshield 26 and body flange 28 having good edge definition. This
substantially eliminates the need for masking of the areas outside of the
desired primer application area, and substantially avoids dripping or
splashing of the liquid primer material onto areas to be left uncoated.
While the invention has been described with reference to a preferred
embodiment, it should be understood by those skilled in the art that
various changes may be made and equivalents may be substituted for
elements thereof without departing from the scope of the invention. In
addition, many modifications could be made to adapt a particular situation
or material to the teachings of the invention without departing from the
essential scope thereof. Therefore, it is intended that the invention not
be limited to the particular embodiment disclosed as the best mode
contemplated for carrying out this invention, but that the invention will
include all embodiments falling within the scope of the appended claims.
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